Supplementary Material for: Speed of Voluntary Step Execution May Predict Survival Among Older Adults – An Explorative Study

Objective: With the growing population of older adults, predicting survival through clinical examinations has gained an increased interest. We aimed to evaluate the relationship between balance measures, such as postural sway and voluntary stepping performance and survival. Methods: This study analyzed balance parameters, collected from previous studies conducted between 2005 and 2011, including postural sway, and Stabilogram Diffusion Analysis (SDA) in standing, and voluntary step execution. Cox proportional hazards regression analyses were performed to examine associations between balance parameters and mortality. Results: Voluntary stepping performance, especially under dual-task (DT) condition, was associated with survival. Slower step initiation time was associated with higher mortality risk, with every 0.100 seconds increase, the survival hazard rate ratios decreased by 28%. Postural sway parameters, particularly increase in anterior-posterior sway velocity, demonstrated predictive ability but less effective than voluntary stepping test parameters. Among SDA measures, higher Critical Displacement, tended to show an association with lower survival in older adults. Discussion: These findings align with prior research regarding physical performance indicators, such as gait speed, to survival. Voluntary stepping under DT conditions extends this understanding by capturing both physical and cognitive functions, offering a more integrated survival assessment. Conclusions: Voluntary stepping performance, in DT conditions, may be a valuable predictor of survival in older adults. Incorporating DT based assessments into clinical evaluations could improve survival prediction and guide early interventions targeting cognitive-motor health. Future studies should explore the longitudinal impact of voluntary stepping on survival, assessing whether cognitive-motor training for balance rehabilitation can enhance survival rates.